The proposed studies offer a comprehensive approach for ranking various factors with regard to their relative importance in lack of reflow following microsurgical anastomosis and functional failure of replanted tissue to survive. As an adjunct, the investigators propose to evaluate a number of pharmacologic agents that have shown promise as inhibitors of reperfusion injury and failure. Emphasis will be placed on the functional result after intervention. Specifically, the applicants will: (1) evaluate the effects of low molecular weight heparin alone, and in combination with thrombolytic agents such as streptokinase, urokinase and tissue plasminogen activator, on thrombosis formation at arterial and venous anastomosis sites; (2) determine the effects of specific pharmacologic agents on the microcirculation of innervated and denervated tissues after reperfusion injury with emphasis on leukocyte adhesion and migration; and (3) quantify effects of specific pharmacologic agents on innervated and denervated muscles with different fiber types. Subsequent function of the muscles will be measured by contractile ability along with PMN adherence and nitric oxide and nitric oxide synthase activity.